What is the general definition of emf?

In summary, there are three types of emf that are commonly mentioned in textbooks. The first two types are similar in that they involve a stationary power source or a moving conductor in a magnetic field, respectively. The third type involves a closed loop encircled by a changing magnetic field and is defined as the line integral of "E dot l" around the loop. However, there seems to be a lack of a general definition of emf, as different cases may have slightly different meanings. To resolve this issue, one can refer to Wikipedia, where the definition of emf includes both magnetic and electric forces, as well as thermal and chemical forces.
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kelvin490
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I have little problem in understanding emf in a circuit. There are three types of emf mentioned in textbooks and the first two are very similar:

1. The emf provided by a battery or other stationary power source. The emf is actually the voltage difference provided to the circuit.

2. The emf provided by a moving conductor in magnetic field.It is the work done to raise a charge to higher potential.

3. The work done to move a charge around a stationary loop encircled a changing magnetic field.

In the third case, the emf is defined as line integral of "E dot l" around a closed loop. However, in the second case, it doesn't make any sense to do the same integral around the circuit because in the moving conductor the force is magnetic but in the rest of the circuit the force is electrostatic in nature (because the charge accumulated on the two sides of moving conductor). So the line integral is only for the the part that is moving. It seems that there is a lack of general definition of emf because it different cases it means slightly different things. How to resolve this problem?
 
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What is the general definition for emf?

The general definition for emf, or electromotive force, is the potential difference between two points in an electrical circuit. It is measured in volts and represents the amount of energy that is converted from electrical to other forms, such as mechanical or heat energy.

What is the difference between emf and voltage?

Emf and voltage are often used interchangeably, but they have different definitions. Emf is the total amount of energy converted from electrical to other forms, while voltage is the potential difference between two points in a circuit that drives the flow of electrons.

How is emf calculated?

Emf is calculated by multiplying the current and resistance in a circuit. This can also be represented by the equation emf = I x R, where I is the current and R is the resistance.

What is the unit of measurement for emf?

The unit of measurement for emf is volts (V). This represents the amount of energy per unit charge that is converted from electrical to other forms.

What are some real-life applications of emf?

Emf has many real-life applications, such as in batteries, generators, and solar cells. It is also used in machines and devices that convert electrical energy to other forms, such as motors and heaters.

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